1. Field of the Disclosure
The present invention relates to a method of fabricating a semiconductor device, and more particularly, to methods of correcting defects in photomasks.
2. Brief Description of Related Technology
A photomask is used to form a pattern on a wafer during a process of fabricating a semiconductor device. The photomask is used to transfer a pattern of a mask on a wafer through a photolithography process. Accordingly, processes of fabricating a photomask are regarded as very important operations. To fabricate a binary mask, a light blocking layer and a resist layer are formed on a transparent substrate. A light exposure process and a development process are performed to form a resist pattern that selectively exposes the resist on the light blocking layer. Using the resist pattern as an etching mask, the exposed light blocking layer is etched to form a light blocking pattern, and then the remaining resist pattern is removed.
While a photomask is formed, pin hole defects can occur due to equipment malfunctions. A pin hole defect results from a portion of the light blocking layer not forming where it is supposed to form. This pin hole defect may allow transmission of light during a wafer exposure process, thereby causing defective patterns. If the pin hole defect occurs, a method through a focused ion beam (FIB) can be used to correct the pin hole defect. Because the FIB corrects the pin hole defect locally, additional defects or damage may occur due to correction equipment. Additionally, if the size of the pin hole defect is more than several hundred micrometers (μm), there are limitations in correcting it locally.